#region Copyright
/// <copyright>
/// Copyright (c) 2007 Ilia Shramko.
/// Released under the terms of the GNU General Public License.
/// </copyright>
#endregion

using System;
using System.Text;

namespace Osh.Dvb
{
	/// <summary>
	/// Summary description for DvbUtil.
	/// </summary>
	public static class DvbUtil
	{
		private static uint[] _crcTable = new uint[256]
		{
			0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9, 0x130476dc, 0x17c56b6b,
			0x1a864db2, 0x1e475005, 0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
			0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd, 0x4c11db70, 0x48d0c6c7,
			0x4593e01e, 0x4152fda9, 0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
			0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011, 0x791d4014, 0x7ddc5da3,
			0x709f7b7a, 0x745e66cd, 0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
			0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5, 0xbe2b5b58, 0xbaea46ef,
			0xb7a96036, 0xb3687d81, 0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
			0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49, 0xc7361b4c, 0xc3f706fb,
			0xceb42022, 0xca753d95, 0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
			0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d, 0x34867077, 0x30476dc0,
			0x3d044b19, 0x39c556ae, 0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
			0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16, 0x018aeb13, 0x054bf6a4,
			0x0808d07d, 0x0cc9cdca, 0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
			0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02, 0x5e9f46bf, 0x5a5e5b08,
			0x571d7dd1, 0x53dc6066, 0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
			0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e, 0xbfa1b04b, 0xbb60adfc,
			0xb6238b25, 0xb2e29692, 0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
			0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a, 0xe0b41de7, 0xe4750050,
			0xe9362689, 0xedf73b3e, 0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
			0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686, 0xd5b88683, 0xd1799b34,
			0xdc3abded, 0xd8fba05a, 0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
			0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb, 0x4f040d56, 0x4bc510e1,
			0x46863638, 0x42472b8f, 0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
			0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47, 0x36194d42, 0x32d850f5,
			0x3f9b762c, 0x3b5a6b9b, 0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
			0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623, 0xf12f560e, 0xf5ee4bb9,
			0xf8ad6d60, 0xfc6c70d7, 0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
			0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f, 0xc423cd6a, 0xc0e2d0dd,
			0xcda1f604, 0xc960ebb3, 0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
			0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b, 0x9b3660c6, 0x9ff77d71,
			0x92b45ba8, 0x9675461f, 0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
			0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640, 0x4e8ee645, 0x4a4ffbf2,
			0x470cdd2b, 0x43cdc09c, 0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
			0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24, 0x119b4be9, 0x155a565e,
			0x18197087, 0x1cd86d30, 0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
			0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088, 0x2497d08d, 0x2056cd3a,
			0x2d15ebe3, 0x29d4f654, 0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
			0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c, 0xe3a1cbc1, 0xe760d676,
			0xea23f0af, 0xeee2ed18, 0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
			0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0, 0x9abc8bd5, 0x9e7d9662,
			0x933eb0bb, 0x97ffad0c, 0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
			0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
		};

		private static LanguageCode LanguageCodeFromString(string language)
		{
			if(language.Length != 3)
				throw new ArgumentOutOfRangeException("language");
			return (LanguageCode)(((byte)language[0] << 16) | ((byte)language[1] << 8) | (byte)language[2]);
		}

		public static string LanguageCodeToString(LanguageCode languageCode)
		{
			int languageCodeValue = (int)languageCode;
			StringBuilder sb = new StringBuilder(3, 3);
			sb.Append((char)(languageCodeValue >> 16));
			sb.Append((char)((languageCodeValue >> 8) & 0xFF));
			sb.Append((char)(languageCodeValue & 0xFF));
			return sb.ToString();
		}

		public static int GetLanguageCodePage(LanguageCode languageCode, int defaultCodePage)
		{
			int codePage = GetLanguageCodePage(languageCode);
			return codePage != 0 ? codePage : defaultCodePage;
		}

		public static int GetLanguageCodePage(LanguageCode languageCode)
		{
			int codePage;
			switch(languageCode)
			{
				case LanguageCode.Cze:
				case LanguageCode.Dan:
				case LanguageCode.Deu:
				case LanguageCode.Dut:
				case LanguageCode.Eng:
				case LanguageCode.Est:
				case LanguageCode.Fin:
				case LanguageCode.Fra:
				case LanguageCode.Fre:
				case LanguageCode.Ger:
				case LanguageCode.Hrv:
				case LanguageCode.Hun:
				case LanguageCode.Ita:
				case LanguageCode.Lat:
				case LanguageCode.Nld:
				case LanguageCode.Pol:
				case LanguageCode.Por:
				case LanguageCode.Rom:
				case LanguageCode.Scc:
				case LanguageCode.Slv:
				case LanguageCode.Spa:
				case LanguageCode.Srp:
				case LanguageCode.Swe:
					codePage = 28592;
					break;

				case LanguageCode.Kat:
				case LanguageCode.Geo:
				case LanguageCode.Lit:
				case LanguageCode.Slk:
				case LanguageCode.Slo:
					codePage = 28594;
					break;

				case LanguageCode.Bel:
				case LanguageCode.Bul:
				case LanguageCode.Rus:
				case LanguageCode.Ukr:
					codePage = 28595;
					break;

				case LanguageCode.Ara:
					codePage = 28596;
					break;

				case LanguageCode.Ell:
				case LanguageCode.Grc:
				case LanguageCode.Gre:
					codePage = 28597;
					break;

				case LanguageCode.Heb:
					codePage = 28598;
					break;

				case LanguageCode.Tur:
					codePage = 28599;
					break;

				default:
					codePage = 0;
					break;
			}
			return codePage;
		}

		public static DateTime DecodeDateTime(byte[] data)
		{
			return DecodeDateTime(data[0], data[1], data[2], data[3], data[4]);
		}
		
		public static DateTime DecodeDateTime(byte d1, byte d2, byte h, byte m, byte s)
		{
			double MJD = d1 << 8 | d2;

			int Y = (int)((MJD - 15078.2) / 365.25);
			int M = (int)((MJD - 14956.1 - (int)(Y * 365.25)) / 30.6001);
			int D = (int)MJD - 14956 - (int)(Y * 365.25) - (int)(M * 30.6001);
			int K = (M == 14) || (M == 15) ? 1 : 0;
			Y = Y + K;
			M = M - 1 - K * 12;

			if(Y < 0 || M > 12 || D > 31)
				throw new ArgumentOutOfRangeException("d1");

			return new DateTime(Y + 1900, M, D) + DecodeTimeSpan(h, m, s);
		}

		public static TimeSpan DecodeTimeSpan(byte h, byte m, byte s)
		{
			int hh = (h >> 4) * 10 + (h & 0xF);
			int mm = (m >> 4) * 10 + (m & 0xF);
			int ss = (s >> 4) * 10 + (s & 0xF);

			if(hh < 0 || hh >= 24)
				throw new ArgumentOutOfRangeException("h");
			if(mm < 0 || mm >= 60)
				throw new ArgumentOutOfRangeException("m");
			if(ss < 0 || ss >= 60)
				throw new ArgumentOutOfRangeException("s");

			return new TimeSpan(0, hh, mm, ss);
		}

		/// <summary>
		/// Decodes PTS or DTS timestamp of PES stream.
		/// </summary>
		/// <param name="buffer">Buffer which contains timestamp encoded according ISO/IEC 13818-1 (5 bytes).</param>
		/// <param name="position">Position in the buffer where the timestamp starts.</param>
		/// <returns></returns>
		public static Timestamp DecodeTimestamp(byte[] buffer, int position)
		{
			long bits32_30 = (buffer[position] >> 1) & 7;
			long bits29_15 = ((buffer[position+1] << 8) | buffer[position+2]) >> 1;
			long bits14_0 = ((buffer[position+3] << 8) | buffer[position+4]) >> 1;
			long result = (bits32_30 << 30) | (bits29_15 << 15) | bits14_0;
			return new Timestamp(result);
		}

		public static bool CheckCrc32(byte[] buffer, int offset, int count)
		{
			uint crc = 0xFFFFFFFF;

			for(int i = 0; i < count; i++)
				crc = (crc << 8) ^ _crcTable[((crc >> 24) ^ buffer[offset++]) & 0xFF];

			//System.Diagnostics.Debug.Assert(crc == 0);
			return crc == 0;
		}


	}
}
